Page 2 - Mobo Power is ALWAYS ON and POST fails

Different motherboards respond to uncommanded power-off situations differently. Some will restart once power is reapplied, assuming an unscheduled power outage, others will remain in the default off-state until the power button is hit. Most have an option in the BIOS to control this behaviour.

If the machine turns on and POSTs, then try turning it off using the power button. After that, then reapplying PSU power should result in th emachine staying off until commanded otherwise.

If the machine doesn't POST, then chances are there is a hardware failure of some sort. Check all connections to be sure a wire or two isn't in the wrong position, look for unintended shorts to chassis and such.